s/keys vs s/map-of

[olivergeorge]

It'd be nice to have a way to indicate a spec key which should be treated as s/map-of instead of s/keys

[stathissideris]

The latest version implements something related to this (but not exactly this): maps where the keys are not keywords are automatically inferred as s/map-of because s/keys does not support non-keyword keys anyway. This case used to make spec-provider fail.